Yes but we should not look at unicorns to settle this argument. After all not every company has the size of a unicorn, the world is not big enough for that. Very few companies get to the point that any random technology won't do.
I've seen dozens of Rails projects going in production and many are still there. Same thing for any other programming language I guess. For normal sized companies Rails is OK.
What matters is: do you still find developers to work with your technology after 2, 5, 10, 20 years? If you don't, you have to move the project where the developers are. In the case of Rails they are still here for hire.
I don't know if anyone needs to think about 20 years from now anymore with the new A.I advancements we see on a monthly basis. I'd be surprised if humans still wrote code 20 years from now but we'll see...
I've seen dozens of Rails projects going in production and many are still there. Same thing for any other programming language I guess. For normal sized companies Rails is OK.
What matters is: do you still find developers to work with your technology after 2, 5, 10, 20 years? If you don't, you have to move the project where the developers are. In the case of Rails they are still here for hire.